Jamming of active particles in narrow pores: implications for ratchet effect and diffusion coefficient

We study the behavior of colloidal active particles interacting via steric repulsion in various quasi-one-dimensional geometries. We mainly focus on active particles with a high Péclet number. We discuss three phenomena closely tied to these systems: motility-induced phase separation (or dynamical freezing), the ratchet effect (which takes place if the geometry has broken spatial symmetry), and the enhanced diffusion coefficient. We study these particles using numerical simulations, employing an asymmetric simple exclusion process (ASEP)-like model. In addition to direct numerical simulations, we study the model by mean-field approximation and by solving the coarse-grained hydrodynamic equations.